不同雨强条件下坡度对坡地产汇流及溶质运移的影响

为了分析坡度对坡面产汇流和溶质运移的影响,以室内土槽为平台,采用人工模拟降雨实验,研究了坡度为5°,10°和15°,雨强为30,60和120 mm/h条件下植被坡地的入渗总量、坡面流流速、地面径流以及地面径流中Br-,NH4+和NO3-的浓度变化.结果表明,在其它影响因素相同的情况下,随着坡度的增大,坡面平均流速增大,地面径流总量增加,入渗总量减少、地面径流初始产流时间和径流终止时间均呈减小趋势,地面径流中Br-浓度变化不大,变化曲线几乎重合,NH4+浓度总体上呈递减趋势,且随着降雨强度的增大,这种递减趋势越显著,NO3-的规律性不明显.用幂函数关系可较好地拟合出坡面平均流速与坡度的关系.

Influences of Slope on Runoff and Concentration and Solute Transport Under Different Rainfall Intensities

In order to analyze the influences of land surface slope on runoff and concentration and solute transport,the total infiltration amount,the average of overland flow velocity,surface runoff and the changes of Br-,NH4+,and NO3-concentrations in surface runoff were studied in indoor soil tank experiment under artificial rainfall simulation. Three slopes (5°,10°,and 15°) and three rainfall intensities (30,60 and 120 mm/h ) are tested. Results show that with slope increasing,the average of overland flow velocity and the total amount of surface runoff are increased and the beginning time and termination time of surface runoff are advanced. The total infiltration amount is decreased with slope increasing. No obvious change in Br-concentration is observed and the course lines of Br^-concentration in surface runoff are almost coincident. The NH⁺₄ concentration appears a reducing trend and this trend becomes obvious with rainfall intensity increasing. Change of NO^-₃ concentration is not evident. The relationship between the averaged overland flow velocity and surface slope expressed by simple power function.